Ammonia-cyanid process of treating ores containing precious metals.



umrsn simrss rnrnur OFFICE.

DAVID MOSHER, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO AMMONIA OYA NIBI ENGINEERING COMPANY, 'OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OFCALIFORNIA.

mmonia-cramp success or 'rn'nA'rINe ones conzramrne- .enncrous rams.

Specification of Letters Patent.

Patented Feb. 2, 1908.

Application filed September 4, 1907. Serial No. 391,878.

' Precious Metals, of which the following is a and silver, suchammonia-soluble metals as os'es,

specification.

My invention relates to the treatment of ores and tailings with ammoniacyanid solutions, forthe purpose of extracting their gold and silvercontent. I

- My inventionis applicable, not only to the treatment of ores andtailings containing gold and silver alone, but also to such ores andtailings as contain, in addition to gold er, zinc, nickel and cobalt.

e object of my invention is to effect economy in the process; and, tothis end, my invention consists in the treatment of the ores and tailins with a solution of ammonia and an alka ine earth-metal cyanid, as Ishall now fully describe.

In the treatment of ordinary gold and silver bearing ores and tailingsby the cyanid process, a cyanid solv nt must be used whichis not onlystable in dilute solutions, such as 0.05% to 0.50% KCy, but mustwithstand exposure to the atmosphere as well, without decomposition. Itmust also not contain im urit'ies, such as sulfids, carbids, etc., Whicwould greatly depress the I gold and silver extraction co-eflicient ofthe cyanid solvent, The cyanide ordinarily used, therefore are, thepotassium and sodium salts, K23 and Na y. These are highly refined,snow-white and almost chemicall pure. In this state they are sent to marst for precious metal extraction purand are, necessarily, ver costly, om20 to 25 cents per pound. 11 recent years, however, there has-been greatdevelopment in the cheap productionof alkaline earth-metal cyanids, suchas calcium cyanid, Ca(Cn),, and barium cyanid, Ba(Cn),, by means of theelectric furnace, from atmospheric nitrogen. I" have found that theseelectric furnace products, even 1mpure as tion of alifinonia, 1% or theyare, if they contain 80% to 90% of the thcoretical'quantity of cyanogen(Cn),', are available for and may be ado ted and used in ammoniasolutions, as go (1 and silver solvents.

In carrying out my invention, the crude calcium cyanid or barium cyanidis dissolved in ammonia solution of sufficient strength; the insolubleresidue allowed to settle and the clear solution applied in thetreatment of gold and silver bearin ores and tailings, not amenable toor inary oyanid treatment, either on account of excessive cyanidcomsumption due to cyanicides, or on account of percentage of metalssuch as copper, nickel, zinc or cobalt, which j render inert the gold orsilver solvent owers of a dilute cyamd solution (KCy or aCy) such as iscommonly used, and cause an excessive loss of'the cyanid. i

A Working'solution, according to my invention, may be made u as follows:Solu- I less to 10% (NH), Calcium evanid or barium cyanid, 0.05% to 1%.If this solution be too alkaline, a salt of ammonia, s"uch as thesulfate, may be added to counteract such excessive alkalinity. Thetreatment of the ores or tailings with this solution is carried out manyof the usual or known manners, as by laching oragitating them with suchsolution; and, where the ores or tailings contain, in addition to thegold and silver values, such metals as copper, nickel, zinc or cobalt,all these metals Including the oldand silver are simultaneously extractsand the se arationof the gold and silver afterwar s effected in anyordinary manner.

It will be seen that by my im rovement, a ver cheap gold and silver sovent is obtaine which overcomes all the objections and conditions abovereferred to.

Havin thus described my invention, what I' c aim as new and desire tosecure by Letters Patent is,

1. The improvement tailings containing gold and silver, which intreating ores and.

'with a solution of ammonia and an alkaline earth-metal cyanidi 2. Theimprovement in treating copper, I name to this specification in thepresence of nifiel, zilnc 1nd cobailt ores 311% tailings with twosubscribing Witnesses.

0 an sliver Va ues, w ic consists in 1 s imultancously extracting 12,11the metals DAVID" MObHER 5 with a, solutiqn of ammonia and. an alkalineWitnesses:

each-metal cyanid. A v N. A. AOKER,

111 "castimony'wherecf I hav signeax my D. B. RICHARDS.

